Try submerging or smearing your samples (Al layer side!) with  o-phosphoric
acid with some mild temperature elevation of the o-phosphoric acid will
increase the rate of etching. Then rinse off with DI water. However, before
trying this on your "best" samples try a few dummy runs first.


******************************
* Karl H. Cazzini (Ph.D)     *
* Conifer Group & Associates *
* 116 Cochituate Road        *
* Framingham MA 01701        *
* USA                        *
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* Tel(W): (508) 620 8845     *
* Fax(W): (508) 620 8830     *
* Tel(H): (508) 875 2009     *
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-----Original Message-----
From: mems-mgr@ISI.EDU [mailto:mems-mgr@ISI.EDU]On Behalf Of Geng Chen
Sent: Monday, January 11, 1999 8:29 PM
To: MEMS@ISI.EDU
Subject: Selective release etch of Al sacrificial layer


Hi there,

We would like to release an Al sacrificial layer (0.5 5m thickness) without
affecting any
other metal and dielectric layers in the structure.  An undercut rate of 100
5m+ in 10
min. is required.  The etchant should not attack PE oxide, nitride, Ti, Au.
Any suggestions?
Your help will be very much appreciated.
Regards,

G. Chen